In a U.S. Senate race already setting up to be particularly rugged, one factor for a pair of Republican congressman could be just how well they can show who is most loyal to President Trump

The president didn’t exactly leave anything to the imagination, either, about where he was coming from.

In a speech-turned-political rally before Boy Scouts gathered for the National Jamboree in West Virginia, Trump found himself reciting Scout Law, allowing room for a trademark aside after getting as far as “trustworthy, loyal …”: “We could use some more loyalty, I will tell you that.”

But in Donald Trump’s world, and in his White House, loyalty tends to be expected to be a one-way street. Last week was no exception. Attorney General Jeff Sessions, who as a senator stood alone as Trump’s earliest congressional champion, was called out on the president’s Twitter feed for recusing himself from the investigation into possible Russian interference in the 2016 election and humiliated for not going after Hillary Clinton’s emails. Reince Priebus was shown the door as chief of staff amid talk about White House leaks to the media. Senators who didn’t come through on the failed health care reform bill were threatened openly and often, in various ways.

It’s clear that when they take a break from calling the other “unhinged” – yes, both campaigns have lobbed that word at the other at some point – they’ll be chasing the Trump vote, trying to out-Trump the other in so many ways.

The day the pro-Rokita letter went out from Rex Early and Tony Samuel, the Trump Indiana chairman and vice chairman, Messer was doing what he could to drop Trump’s name. A Thursday press release touted Messer’s vote for the Make America Secure Appropriations Act, which included $1.57 billion in funding “for President Trump’s border wall.” With Trump rallies still ringing in his ears, perhaps – “Build that wall! Build that wall!” – Messer’s release pegged him as “an early advocate of Trump’s border wall, urging Congress to provide for immediate construction back in January.” (The release doesn’t indicate that the bill would be passed along to the Mexican government, as Trump promised on the campaign trail … but I digress.)

In other words, think what you will, read what you can and rail all you want about the Donald Trump White House. But underestimate his pull in this state – one he won by 19 percentage points in November – at your own risk.

To read Early and Samuels’ letter, the loyalty card goes to the one who committed first, a seeming poke at Messer toying with discussions of potential “white knight” candidates when there was talk about staging a GOP convention coup last summer.

“We heard from several of you about your frustration with Republican officeholders and candidates that criticized Donald Trump whenever they felt it was politically expedient for them or whenever things got heated in the media,” Early and Samuels wrote to Trump supporters in Indiana. “Of the members of Indiana’s congressional delegation, Todd Rokita is the only one that actively and specifically campaigned for candidate Trump – never wavering and never jumping on and off the Trump Train.”

That’s the thing about the Trump Train, though: You buy the ticket, you take your chances.

It comes with the constant promise of a request for a reaction: So, the president said this, do you think that, too?

There will be something else tomorrow. And the next day. And the next. That’s just how the Trump presidency has worked six months in.

U.S. Rep. Luke Messer(Photo: IndyStar 2010 file photo)

Is the Rokita camp worried about the blowback? Is it a strategy that works in the primary but will have to be moderated in time for independent voters who will be there in a general election, the way Richard Mourdock had to reel in his “no-compromise” message used to take down long-time U.S. Sen. Richard Lugar in 2012?

Not really, said Tim Edson, a strategist with Hoosiers for Rokita.

“President Trump is attempting to follow through on an agenda that won Indiana by nearly 20 points,” Edson said. “He needs more partners in the House and Senate. The real risk is for Joe Donnelly, someone who has always voted in lockstep with (Barack) Obama, Hillary and (Nancy) Pelosi on all the big issues—Obamacare, taxes, the Iran deal, guns and life. Will the Indiana electorate have moved that far in two years? Seems unlikely.”

As for the GOP primary, nine months away in May, Edson didn’t hold back about how the Trump campaign’s words for Rokita might be used. It picks up on themes the Rokita campaign – not even formally announced at this point – has been using to paint Messer as a certain kind of Republican.

“It’s not about who can out-Trump the other, it’s about the truth,” Edson said. “Grassroots conservatives are sick to death of Republican elites telling them to get in line behind an establishment candidate, only to have the same people – and Luke Messer is one to the core – trash Donald Trump with the talking points of elites, the media and Democrats after it was clear Trump was going to be the GOP nominee.”

Messer has protested the way Rokita has attacked, capitalizing on revelations that Messer’s wife, Jennifer, had a contract with the city of Fishers for $240,000 a year as a part-time attorney; that Messer moved his family to suburban Washington, D.C.; and that suspicious edits on Messer’s Wikipedia page put him in a less-than-favorable light.

“It’s clear that (Rokita) will do and say almost anything to advance his political career,” Messer recently wrote to his supporters.

Here in the 4th District, that rings true. Saying anything has always been right in Rokita’s wheelhouse. In a statewide race with huge national implications, the rest of Indiana is about to find that out, too.